In the operation of mixing medicinal solutions, the medicinal solution in a vial is manually aspirated into a syringe to discharge the medicinal solution in the syringe. When medicinal solutions are mixed in a hospital, a plurality of operations are often performed at one time. Accordingly, it is quite a workload for a mixing person to push and pull a plunger with respect to a syringe in order to mix the medicinal solutions. For the purpose of reducing the workload of the mixing person, it has been considered a syringe drive device, which causes a plunger to be pushed and pulled by drive power of a motor.
There is a syringe drive device (infusion solution transfer device) that causes a plunger to be pushed by drive power of a motor, although it is not a device used in mixing operations (refer to JP 2004-73373 A).
FIG. 22(a) is a sectional view showing a main portion of an infusion solution transfer device 1 disclosed in JP 2004-73373 A, in a state where a syringe is attached. By moving a drive shaft 2 that is coupled to a drive mechanism such as a motor, a plunger holder 3 is linearly moved. When the plunger holder 3 pushes the plunger 4, a medicinal solution in a syringe 5 is discharged from an injection port.
The infusion solution transfer device 1 includes a flange attachment 8 used for fixing a flange 7 of an outer tube 6 of the syringe 5. The flange attachment 8 has a flange front surface support portion 9 which is fixed, and a flange rear portion presser plate 10 which is movable, so that the flange 7 having a different thickness can be fixed reliably. FIG. 22(b) is a sectional view showing a main portion of the infusion solution transfer device 1 in a state where the syringe 5 is not attached. When a knob 11 is operated, the flange rear portion presser plate 10 is rotated and can move close to and away from the flange front surface support portion 9. Therefore, the flange rear portion presser plate 10 can push the flange 7 having a different thickness against the flange front surface support portion 9.
The infusion solution transfer device 1 (syringe drive device) thus configured has a problem that, after the plunger 4 is pushed toward the outer tube 6, the syringe 5 is held between the flange front surface support portion 9 and a press surface 12 of the plunger holder 3, with a result that the syringe 5 cannot be easily detached.
The syringe 5 is held for the following reason. When the plunger 4 is pushed by the plunger holder 3, the outer tube 6 is frictioned with a gasket that is provided at a distal end of the plunger 4. Accordingly, as indicated by an arrow P1 in FIG. 22(a), the outer tube 6 tends to move forward (toward the injection port of the syringe 5) together with the plunger 4. On the other hand, as indicated by an arrow P2 in FIG. 22(a), the flange front surface support portion 9 prevents the forward movement of the flange 7 against the force (arrow P1) of the plunger holder 3 to push forward the plunger 4. In other words, the flange front surface support portion 9 and the press surface 12 of the plunger holder 3 press the flange 7 of the syringe and a brim 4a of the plunger 4 in directions opposite to each other. As a result, the syringe 5 is held between the flange front surface support portion 9 and the press surface 12 of the plunger holder 3.
Particularly in a state where the plunger 4 is pushed to the limit (a state where the gasket provided at the distal end of the plunger 4 is in contact with a front wall surface 13 of the outer tube 6), the syringe 5 is rigidly held by the force of the plunger holder 3 to push the plunger 4. Accordingly, it is more difficult to detach the syringe 5 in this state.
Further, in this infusion solution transfer device 1, the flange 7 is held between the flange front surface support portion 9 and the flange rear portion presser plate 10 to fix the syringe 5. Thus, the syringe 5 is fixed only in the axial direction thereof, and the syringe 5 is not sufficiently fixed in the detached direction.